mfd: cgbc-core: Fix error handling paths in cgbc_init_device()

mfd: cgbc-core: Fix error handling paths in cgbc_init_device()

If an error occurs after a cgbc_session_request() call, it should be
balanced by a corresponding cgbc_session_release(), as already done in the
remove function.

Fixes: 6f1067cfbee7 ("mfd: Add Congatec Board Controller driver")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Thomas Richard <thomas.richard@bootlin.com>
Link: https://lore.kernel.org/r/83194335554146efc52c331993f083bd765db6f9.1730205085.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Lee Jones <lee@kernel.org>